Police say a Ford-150 pickup hit Officer Bruce St. Laurent's motorcycle in West Palm Beach as he prepared to shut down a section of Interstate 95.
He was taken to nearby St. Mary's Medical Center and was pronounced dead.
Obama was on the second day of a bus tour through the key swing state and made a campaign appearance Sunday at the Palm Beach County Convention Center.
White House press secretary Jay Carney said that while the president didn't see the accident, he was notified of the officer's death and said "our thoughts and prayers are with the officer's family."
St. Laurent, 55, was a 20-year veteran of the Jupiter Police Department.
The Associated Press contributed to this report.